a. Field of the Invention
This invention relates to a magnetic head having a good reproducing frequency characteristic.
B. Description of the Prior Art
Generally considered, the primary factors which affect the reproducing frequency charactristic of a magnetic head include the core loss resulting from the eddy current loss and the gap loss attributable to the operating gap width of the core. In the conventional method of making a magnetic head, a greater number of thin layers are used to form the core as a better frequency characteristic is desired and, thereby, the core loss can be reduced to a negligible extent. Thus, efforts have heretofore been devoted solely to reducing the gap loss in improving the reproducing frequency characteristic of the magnetic head.
In making a magnetic head, it is a requisite to form the core with a uniform gap width which ensures the best reproducing frequency characteristic as noted above, but as a matter of course, errors occur in the operating gap width of the core depending on the manufacturing technique and it has been extremely difficult to to minimize such errors, say, to 0.5 .mu.m or less, even in the magnetic heads produced on a mass production scale by the best manufacturing method available at present.
However, as the recording wavelength of the tape approaches the operating gap width of the magnetic head on which a magnetic tape slides, the reproducing frequency characteristic of the magnetic head is greatly aggravated by the gap loss Lg which is represented by the following ##EQU1## WHERE G IS THE OPERATING GAP WIDTH AND .lambda. THE RECORDING WAVELENGTH. Therefore, the above-mentioned variation in the operating gap width seriously affects the reproducing frequency characteristic, and this has become a very serious problem in considering the characteristic of a tape recorder, such as especially a cassette tape recorder, in which the tape speed is slow but the required upper limit of the reproducing frequency has become 10 to 16 KHz, and it has thus become desirable to minimize the influence imparted to the reproducing frequency characeristic by the variation in the operating gap width.